The deleterious effects of compositions containing surfactants upon keratin are well-known. These effects are caused, it is thought, by penetration of the surfactant into the keratin surface leading to "leaching out" of oils and moisturising components essential for good condition of the keratin. This penetration by surfactant and "leaching out" of essential oils also affects the ability of the keratin, particularly in the case of skin, to retain water within the tissue and this again leads to poor condition of the keratinous material.
Compositions containing surface-active agents and providing greatly enhanced conditioning benefits over previous formulations, are described in the commonly assigned German Patent Application No. DOS 2434063 filed July 16, 1974, and published on Feb. 6, 1975, the disclosures of which are specifically incorporated herein by reference. According to this Application, certain proteins modified in specific ways have been found to improve the emolliency of detergent compositions containing them and such compositions successfully meet the twin objectives of improved mildness and conditioning characteristics, with maintained lathering and detergency characteristics.
One problem posed by the use of proteins in detergent compositions, however, stems from the fact that proteins, even at relatively low concentration, can have quite large effects on the physical characteristics of the compositions, despite the fact that their basic cleaning characteristics may be substantially unimpaired. Such effects may take, for instance, the form of increased viscosity of liquid formulations or decreased ease of solution of granular formulations. Clearly, it would be of advantage to increase the conditioning benefit/protein level efficiency so as to either increase the maximum level of conditioning benefit inherent in a given type of protein formulation, or so as to achieve a given level of conditioning benefit from a reduced content of the protein. In the latter case, conditioning and detergency characteristics may be optimized without having an undue effect on the physical characteristics of the base detergent formula.
Thus, one object of the present invention is the provision of protein-containing detergent compositions having significantly improved emolliency and conditioning benefits, in which the efficiency of such benefits for a given level of protein is improved. A further object of the invention is the provision of protein-containing detergent compositions in which the effect of the protein on the physical characteristics of the detergent composition is reduced.